From 2008-2015, 2.9 million immigrants have been deported from the U.S. Over half of them are parents of U.S. citizen children. Parental deportation can have profound and long-lasting consequences for the children left behind. To our knowledge, no large-scale, longitudinal, and population-based study has examined the short- and long-term effects of parental deportation on the health and well-being of U.S. citizen children of deported immigrants. The aim of this 2-year mixed-methods pilot study is to develop and test a novel methodology to conduct such a study in the near future. We will use an ambidirectional cohort design with an external comparison cohort. A probability-based sample of deported Mexican immigrant (index) parents [(n=50)] will be recruited at the deportation stations in Tijuana, Nogales, and Nuevo Laredo, Mexico. At the time of deportation, index parents will serve as ?recruitment brokers? for one of their U.S.-born citizen children and one primary caregiver in the U.S. Matched control non-separated U.S.-born children and a primary caregiver will be recruited from the same communities. Children and primary caregivers will complete a phone survey within 2 weeks from the index parent's deportation and after a 6-month period. Children's physical and mental health, risk and problem behaviors, and academic performance and behavior prior to separation, shortly after deportation, and 6-months after deportation will be assessed and change over time will be compared across children in the two cohorts. Family-, school-, and community-level factors that may mediate or moderate the impact of deportation on child outcomes (e.g., household structure, financial hardship, school quality, and enforcement of immigration policies) will also be assessed. [Qualitative interviews will also be conducted with a subsample of separated children and caregivers (N=10 pairs) to add texture to and validate survey data]. This study will inform the methods of a future large cohort study to determine the impact of deportation policies on the health and well-being of U.S. citizen children of deported Mexican immigrants. Such study will produce critical evidence to inform future immigration policies [and identify programs and services necessary to meet the needs of U.S. citizen children who experience deportation of a parent].